Solar cells are typically fabricated as layers of materials. For example a typical silicon solar cell has a top encapsulating layer made of glass or other clear material such clear plastic to seal the cell from the external environment, a silicon layer having n-type silicon and p-type silicon sub-layers with a pn-junction between them, an optional antireflective layer between the encapsulating layer and the silicon layer, a top grid disposed adjacent the top of the silicon layer (the cathode), and a metal backing layer under the silicon layer (the anode).
Improved photovoltaic efficiency is a continuing goal for wafer-silicon-based photovoltaic cells. Reducing cell thickness is one way to obtain increased efficiency and meet other desirable design criteria, such as reduced weight. Typically, aluminum is used as a full area back reflector and electrical connector for solar cells. However, reducing the thickness of the aluminum reflector may result in significant warping of the cell. Improving photo absorption is another way to improve photovoltaic efficiency. However, many solar cell materials have high reflectance properties, which reduce the amount of photo energy absorbed by the solar cell. What are needed therefore are improved backing structures for solar cells that provide adequate electrical conductivity and physical strength with a reduction in weight, and improved configurations of solar cell materials that reduce reflectance and enhance absorption of solar energy.